The present disclosure relates to the field of displaying technology, in particular to an array substrate and a method for fabricating the same, and a display device.
As shown in FIG. 1, in the course of fabricating display device backplane, aluminum (Al) was first adopted as metal wiring material, for example, as a source electrode and a drain electrode of each of driving Thin-Film Transistors (TFTs). However, as resolution of the backplane increases significantly, wirings made of Al are no longer suitable for new requirements. Elimination of Al wirings in the art is due to the facts that they have a higher electrical resistivity, are prone to electromigration failure, and have Hillock problem during the fabricating process, and other known or unknown defects.
In comparison with Al, copper (Cu) has the following advantages. Firstly, Cu has lower electrical resistivity than Al, which is about 1.7 μΩ·cm lower than 2.7 μΩ·cm of Al electrical resistivity. As a result, lower electrical resistivity can mitigate Interference Resistance (IR) Drop and improve response speed. Secondly, Cu has lower power loss and consumes less energy thanks to its narrow pitch (i.e., wiring width). Thirdly, Cu has a high wiring density, which is good for achieving high definition. Fourthly, Cu has a higher electromigration resistance capability than Al, because of its higher melting point. As a result, Cu has a better electromigration resistance capability than other metals.
Even though Cu has the above good electricity performance, the following problems in terms of mechanics and electricity cannot afford to be overlooked when Cu is introduced as a source electrode, a drain electrode, and wirings. Firstly, Cu is limited by its strong diffusion capability, which may result in failure of TFT devices. Secondly, Cu has a poor bonding strength with SiNx or SiOx (which can be adopted as passivation layer materials). Accordingly, other metals are needed as a transition, which in turn increases the challenges for etching Cu. Thirdly, Cu is prone to being oxidized in an environment of low temperature (less than 200° C.) but hard to produce a compact oxide film that is used to prevent Cu from further oxidization while the oxidization of Cu will cause obvious Mura defect occurs in the display.
Accordingly, when Cu is chosen as wiring material, how to avoid its above deficiencies becomes one of noticeable and urgent technical problems.